Typhoid fever is a bacterial infection caused by Salmonella typhi bacteria. Although rare in industrialized countries, it remains a serious health threat in the developing world, especially for children.
Typhoid fever is transmitted through contaminated food and water or through close contact with an infected person. Risk factors for the infection include poor hygiene and sanitation. Those who travel in areas where the disease is endemic can be infected.
Symptoms of typhoid fever range from mild to severe and usually begin 6 to 30 days after exposure to the bacteria. Symptoms include a high-grade fever often accompanied by weakness, constipation, abdominal pain, and vomiting. Some cases of the infection may cause the sufferer to develop a rash with rose-colored spots.
Symptoms of typhoid fever may last for weeks or even months. Diarrhea is uncommon. Others may carry the bacterium without being affected – making the disease asymptomatic. However, they are still able to transmit the disease to others. The disease is a type of enteric fever, along with paratyphoid fever.
Diagnosis of the infection is by either detecting Salmonella typhi DNA in the blood or by culturing the bacteria or, stool, or bone marrow.
Most people with typhoid fever typically feel better within a few days of starting antibiotic treatment, although some may die of complications. Vaccines against typhoid fever are available, but only partially effective. Vaccines usually are generally reserved for those who may be exposed to the disease or are traveling to areas where typhoid fever is prevalent.
According to the World Health Organization (WHO), between 11 and 21 million cases and 128 000 to 161 000 typhoid-related deaths occur annually worldwide. A similar but often less serious disease, paratyphoid fever, is caused by Salmonella Paratyphi A and B (or uncommonly Paratyphi C).
Causes and Risk Factors of Typhoid Fever
Typhoid is an infection caused by the bacterium Salmonella typhimurium (S. typhi) typically ingested in contaminated food and water or spread between individuals by direct contact with the feces of an infected person
The bacterium invades the intestines and lives in the bloodstream of humans temporarily. The leukocytes (white blood cells) transport the bacteria to the liver, spleen, and bone marrow, where they multiply and reenter the bloodstream. The entire process occurs in about three weeks.
Symptoms develop when the bacteria reenter the bloodstream and proceed to invade the gallbladder, biliary system, and lymphatic tissue of the bowel. The bacteria pass into the intestines and can be determined in cultures obtained from the stool samples tested in the laboratory.
The host’s immune system can do little to fight back because Salmonella typhi can live within the host’s cells which are safe from the immune system.
If left untreated, around 1 in 5 cases of typhoid fever can be fatal. With treatment, less than 4 in 100 cases are fatal.
Animals cannot carry Salmonella typhi; hence, the transmission is always human to human.
Risk factors for typhoid fever include:
- If you work or travel to areas where the disease is endemic
- If you have close contact with someone that has been recently infected with the bacteria.
- If you are a microbiologist handling the bacteria.
- If you drink water contaminated with sewage containing Salmonella typhi.
Signs and Symptoms of Typhoid Fever
Symptoms of typhoid fever typically begin between 6 and 30 days after being exposed to the bacteria.
The two significant symptoms of typhoid are fever and rash. The fever is incredibly high, gradually increasing over several days to temperatures as high as 103–104°F (39–40°C).
The rash is made up of rose-colored spots, particularly around the neck and abdomen. Other symptoms of typhoid fever include:
- Headaches
- Abdominal pain
- Fatigue
- Poor appetite
- Constipation
- Confusion
- Diarrhea
Complications
In severe cases that have been left, the bowel can become perforated. This can result in peritonitis, an infection of the tissue that lines the inside of the abdomen. It is a life-threatening complication that requires immediate attention.
Other complications that could occur include:
- Intestinal hemorrhage due to bleeding. It can be severe but is usually not fatal.
- Encephalitis
- Respiratory diseases such as pneumonia and acute bronchitis
- Kidney and bladder infections
- Psychiatric symptoms delirium and hallucinations, with picking at bedclothes or imaginary objects
- Inflammation of the pancreas (pancreatitis)
- Metastatic abscesses, cholecystitis, endocarditis, and osteitis
- Inflammation of the heart muscles (myocarditis)
Treatment
Antibiotics are used to eliminate the Salmonella typhi bacteria that causes typhoid. Before the use of antibiotics and intravenous fluids, typhoid fever could be fatal with deaths occurring from infection, pneumonia, intestinal bleeding, or intestinal perforation.
Antibiotics have significantly reduced the mortality rate. There is a noticeable improvement within 48 hours on antibiotic therapy and recovery within 7 to 10 days.
The most commonly used antibiotics are ciprofloxacin, azithromycin, and ceftriaxone. It is important to drink adequate water regularly to prevent dehydration. Surgery may be required in more severe cases where the bowel has become perforated.
There is, however, a growing concern with the increasing resistance of Salmonella typhi. The choice of drugs available for the treatment of typhoid fever is fast becoming limited.
In recent years, for example, typhoid fever has become resistant to trimethoprim-sulfamethoxazole and ampicillin.
Ciprofloxacin, one of the more commonly used drugs for typhoid fever, is also experiencing similar difficulties.
Prevention
Public health initiatives that can help prevent and control typhoid fever, such as potable water, improved sanitary practices, and adequate medical care, may be difficult to achieve.
It is believed that vaccinating populations at a higher risk of being infected with the bacteria is the best way to control the disease.
A vaccine is recommended if you live in or you travel to areas where the risk of getting typhoid fever is high.
Vaccines
The vaccines available are;
- One injected in a single dose at least one week before travel.
- Vaccine in the form of capsules, with one capsule to be taken every other day.
Other preventive measures include;
- Regular washing of hands: Frequent hand-washing in hot, soapy water is the best way to control typhoid fever. It is important to wash before eating or preparing food and after using the toilet.
- Do not drink untreated water: Contaminated water sources are a common occurrence where the disease is endemic. For that reason, drink only water that has been treated.
- Avoid raw fruits and vegetables. Because raw produce may have been washed in unsafe water, avoid fruits and vegetables that can’t be peeled. This includes leafy vegetables like lettuce and cabbages.
- Avoid handling food: Avoid preparing food for others if you have been infected, and your doctor no longer considers you contagious.
Sources:
- Typhoid and Paratyphoid Fever; Patient.info
- Factors impacting on the problem of antibiotic resistance; OUP
- Paratyphoid Fever; Wikipedia
- Centers for Disease Control and Prevention; CDC
- World Health Organization; WHO
